1. Field of the Invention
The present invention relates to a method for producing a powder paint, by which a powder paint which has superior properties compared to powder paints obtained by prior methods can be obtained and by which even paint components which are difficult to convert to a powder paint by prior methods can be made into an excellent powder paint.
2. Description of the Prior Art
A powder paint is applied to materials to be painted in the form of a powder and thereafter a coating is formed by heating. Heretofore, a powder paint has been prepared by mechanically grinding the paint components followed by mixing, by mixing the paint components followed by mechanical grinding, by melt-mixing the paint components followed by cooling and mechanical grinding or by mixing the paint components in the presence of a solvent followed by removal of the solvent and mechanical grinding.
In these methods where mechanical grinding is used an expensive apparatus is required for grinding; particles having a uniform particle size are difficult to obtain and homogeneous mixing is difficult to conduct in the powder mixing, which destroys the homogeneity required for the paint. Further, a paint composition containing reactive components is difficult to powder because heat is often applied in the mixing and grinding steps. Further, a paint which provides a metallic-luster and which contains a metal powder loses the metallic-luster in the grinding step and a good quality powder paint can not be obtained since a homogeneous mixing of the powder can not be achieved. In the method where the paint components are dissolved in a solvent and are spray-dried, a deterioration of the paint occurs due to heat and a complicated apparatus is required, which is not suitable for the production of a variety of products, even though no deterioration occurs due to ginding.